FDA staff question Roche drug breast cancer data

WASHINGTON (Reuters) - The benefits of Roche AG's blockbuster drug Avastin may not outweigh risks for patients with advanced breast cancer, U.S. reviewers said in documents released on Friday.

Two studies of Avastin failed to show the same level of benefit for advanced breast cancer patients seen in an earlier trial, Food and Drug Administration reviewers said in a summary prepared for an advisory panel that meets Tuesday.

If the FDA revokes Avastin's approval for breast cancer, the company can no longer promote the drug for breast cancer, but doctors can still prescribe it for that use as it would remain on the market with approval for other cancers.

Avastin won clearance for breast cancer in 2008 under a shorter approval process, but Roche was required to run two follow-up studies to confirm the drug's effectiveness and receive full approval.

Those studies "failed to confirm the magnitude of (progression-free survival) improvement" seen in the initial breast cancer trial, the FDA staff said.

Progression-free survival is the time patients live without their cancer getting worse.

The level of improvement was "not clinically meaningful," the FDA reviewers said, adding that the "risk-benefit ratio" of Avastin plus chemotherapy "may not be considered favorable."

The agency wants input from the advisory panel on "whether clinical benefit has been demonstrated," the summary said.

Kepler Capital Markets analyst Martin Voegtli said the study results were not new and that he expected most panelists to support full approval of Avastin as a first-choice treatment for advanced breast cancer.

A final FDA decision is due by Sept. 17, analysts said.

Roche unit Genentech said its research supported Avastin in advanced breast cancer, and the company is asking the FDA to expand its approval to include use with other types of chemotherapy.

"Avastin is helpful for patients with metastatic breast cancer," Dr. Philippe Bishop, a Roche vice president, said in an interview. "We remain convinced Avastin should be a choice in this setting."